The present invention relates to an apparatus for inserting a thread into a testing position of a tensile strength testing apparatus.
Automatic tensile strength testing apparatus require a mechanism operable automatically to insert the thread to be tested between clamps in a testing frame, that is, for a predetermined number of tensile strength tests.
For this purpose, a known tensile strength testing apparatus has, for example, a rotatable and translatory movable insertion arm carrying a clamp which catches the thread at a predetermined point and which moves along a path which is so oriented that the clamp holding the thread inserts the trailing end of the thread between opened testing clamps. However, such movements of this type of insertion arm require a considerable amount of space and also interfere with the operation of the apparatus because of the movement of the arm which swings back to a great extent.
Other known constructions comprise an endless movable chain with a gripper which catches a prepared thread and inserts it between testing clamps. However, an arrangement of this type can only be used in specific cases, namely, when the testing frame including the testing clamp, is not at the front of the apparatus, as a movable chain would then be an obstacle. Both types of known apparatus also have the disadvantage that the path of movement of the clamp or gripper holding the thread cannot be set towards any random point or be caused to move selectively along any desired path.
The present invention seeks to avoid these disadvantages and provides an apparatus for inserting a thread into the testing position of a tensile strength testing apparatus, whereby at least one thread is maintained ready in a clamping device, the said apparatus comprising an insertion clamp which is vertically movable along a rail which is itself movable to and fro in a horizontal direction in front of the tensile strength testing apparatus by means of a traveling mechanism, thereby permitting unlimited orthogonal movement of the insertion clamp along any desired path.
The insertion apparatus according to the invention provides a number of advantages which either cannot be achieved by known methods or can only be achieved at considerable expense, namely:
(1) there may be different clamping lengths between testing clamps in different installations, but the invention provides the shortest path in each case for the insertion clamp to thereby optimize the operating speed for each installation;
(2) the insertion rate can be controlled in accordance with the invention by superimposing horizontal and vertical movement of the insertion clamp, so that abrupt changes in direction by a slide carrying the insertion clamp may be particularly avoided;
(3) the insertion clamp may, for example, be moved in a circular manner or in a wavy manner, so that it can wind the thread around bolts or position the thread around bolts in a zig-zag line; and
(4) the remainder of the thread may be fed into a suction nozzle while the insertion clamp is passed by such a nozzle.